Do I stare at the edges where its spinning fastest, or the middle? Does the colour appear when you look away (like other optical illusions do) or what? I'm not getting anything. How long am I supposed to stare at it.

Yellow tinge. Probably something to do with how slightly different arrangement of rods and cones in people's retinas. It's why some people can the polarization of light with the naked eye (easiest to see if you look straight up into a clear sky at dusk).